The Representation of the People (Ireland) Act 1868 (31 & 32 Vict. c. 49) was an Act of Parliament in the United Kingdom.
It did not alter the overall distribution of parliamentary seats in Ireland, but did alter their boundaries, including making the electoral constituency of a borough be the same as its municipal boundaries.
References
Representation of the People (Ireland) Act 1868 Wikipedia(Text) CC BY-SA